[Bug 220263]

[Evan Klitzke]

(In reply to David Baron :dbaron: ⌚UTC+2 from comment #45)
> The number of comments recently makes me suspect that something got *worse*
> recently.

Yes, something did change in GNOME recently. Prior to GNOME 3.28 there
was a GTK preference called gtk-application-prefer-dark-theme that could
be used to get dark widgets. This could either be set in ~/.config
/gnome-terminal/gtk-3.0/settings.ini. This was also exposed as a toggle
option in the gnome-tweaks tool, which is probably how most users had
set it it. This GTK option has been deprecated in GNOME 3.28, and the
new way to get a dark theme is to explicitly set one's GTK theme to
Adwaita dark. You can read about this a bit more at [1] and [2].

Firefox apparently has some logic to ignore gtk-application-prefer-dark-
theme, but that logic no longer works on GNOME 3.28 with the Adwaita
dark theme. As was mentioned in comment #43, the work around for GNOME
3.28 is to set a user pref (i.e. in about:config or user.js) that sets
widget.content.gtk-theme-override to Adwaita:light.

As I suspect the overwhelming majority of Firefox users with dark GTK
themes are using Adwaita dark (which is bundled with GNOME), I would
suggest updating the Firefox dark them detection logic to handle the new
case with the Adwait theme names hard coded. This is hacky, but probably
mitigates the issue for most users.

[1] https://jeremy.bicha.net/2017/08/29/gnome-tweaks-3-25-91/
[2] https://jeremy.bicha.net/2018/01/29/gnome-tweaks-3-28-progress-report-1/

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https://bugs.launchpad.net/bugs/220263

Title:
  Bad Firefox integration with dark themes

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